Wittichenite

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Wittichenite
Wittichenite-491887 cropped.jpg
Wittichenite crystal from Mount Gunson , Andamooka ( Lake Torrens ), South Australia, Australia (size: 2.4 × 1.8 × 0.6 cm)
General and classification
other names
  • Copper bismuth ore (also bismuth copper ore )
  • Copper bismuth luster
chemical formula Cu 3 BiS 3
Mineral class
(and possibly department) 		Sulfides and sulfosalts
System no. to Strunz
and to Dana 		2.GA.20 ( 8th edition : II / E.03)
04/03/08/01
Crystallographic Data
Crystal system orthorhombic
Crystal class ; symbol orthorhombic-disphenoidic; 222
Space group P 2 1 2 1 2 1 (No. 19)Template: room group / 19
Lattice parameters a  = 7.723 (10)  Å ; b  = 10.395 (10) Å; c  = 6.716 (5) Å
Formula units Z  = 4
Physical Properties
Mohs hardness 2 to 3
Density (g / cm 3 ) measured: 6.01 (synthetic: 6.19)
Cleavage no
Break ; Tenacity shell-like, brittle
colour steel gray to pewter white; Lead-gray to brassy yellow
Line color black
transparency opaque
shine Metallic luster

Wittichenite , also known under the outdated, mining designation copper bismuth luster or copper bismuth ore , is a rather seldom occurring mineral from the mineral class of " sulfides and sulfosalts ". It crystallizes in the orthorhombic crystal system with the chemical composition Cu 3 BiS 3 and is therefore chemically a copper - bismuth ( bismuth ) sulfide.

Wittichenite is usually found in the form of fine-grained to moderately coarse mineral aggregates from steel-gray to pewter-white in color with black streak color . However, it rarely forms larger crystals from a few millimeters to a few centimeters in size, which have a tabular to short prismatic habit . Fresh samples show a metallic sheen on the surfaces . In the air, the mineral turns lead-gray to brass-yellow after a while.

Etymology and history

Wittichenite was first discovered in the Neuglück mine near Wittichen in the Rottweil district of Baden-Württemberg . The mineral was known there under various names as copper bismuth ore or copper bismuth luster. In 1817, however, after examining some copper bismuth luster, CJ Selb found that this ore consists of two different types of mines that differ in their fracture behavior, color and crystal formation. The latter distinguishing feature prompts Selb to use the terms "dense copper-bismuth ore" and "radiant copper-bismuth ore".

The dense copper bismuth ore was given the name Wittichenite, which is still valid today , in 1853 by Franz von Kobell, according to its type locality, and the radiant copper bismuth ore is referred to as emplektite by Gustav Adolf Kenngott in 1855 .

classification

In the old systematics of minerals according to Strunz (8th edition) , Wittichenite still belongs to the undifferentiated division of "sulfosalts", where it forms a separate group together with Skinnerite .

With the restructuring in the 9th edition of Strunz's mineral systematics , the departments of the class of sulphides were partly redefined and divided more precisely. The mineral is now accordingly in the section of "Sulfoarsenide, Sulfoantimonide, Sulfobismuthide" and there in the subdivision of "Island (Neso) -Sulfarsenide, etc., without additional sulfur (S)", where it is also together with the skinnerite unnamed group forms 2.GA.20 .

The systematics of minerals according to Dana sorts the Wittichenite into the division of " sulfosalts with the ratio 3> z / y and the general composition (A + ) i (A 2+ ) j [B y C z ], where A = metals, B = semi-metals, C = non-metals ". There he forms together with Skinnerit and Moëloit in the unnamed sub-department “03.04.08”.

Education and Locations

Microscopic image of Wittichenite (light gray) segregating with other copper minerals in Bornite (brown), Lady Alice Gold Mine, South Australia

Wittichenite formed in hydrothermally in copper - and bismuth veins , often in paragenesis with other bismuth and copper minerals such as bornite , chalcocite , chalcopyrite , Digenite , djurleite , Emplectite, pyrite , Stromeyerite and Tennantit , but also with aragonite , barite , Calcite , fluorite and rammelsbergite as well as solid bismuth.

Wittichenite has so far been detected at around 260 sites worldwide (as of 2014), including in Argentina , Armenia , Australia , Belgium , Bolivia , Bulgaria , Chile , China , Germany , France , Greece , Greenland , Ireland , Italy , Japan , Canada , Kazakhstan , Mexico , Morocco , Namibia , North Korea , Norway , Austria , Peru , Poland , Romania , Russia , Sweden , Switzerland , Slovakia , Spain , South Africa , Czech Republic , Hungary , United Kingdom (Great Britain) and United States (USA).

Crystal structure

Wittichenite crystallizes orthorhombically in the space group P 2 1 2 1 2 1 (space group no. 19) with the lattice parameters a  = 7.723 (10)  Å ; b  = 10.395 (10) Å and c  = 6.716 (5) Å and 4 formula units per unit cell . Template: room group / 19

See also

literature

  • E. Matzat: Die Kristallstruktur des Wittichenit, Cu 3 BiS 3 In: Tschermaks mineralogische und petrographische Mitteilungen Volume 18, Kapitel 4, 1972, pp. 312-316 ( doi: 10.1007 / BF01082841 ).
  • Paul Ramdohr , Hugo Strunz : Klockmann's textbook of mineralogy . 16th edition. Ferdinand Enke Verlag, 1978, ISBN 3-432-82986-8 , pp. 474 .
  • Petr Korbel, Milan Novák: Encyclopedia of Minerals . Nebel Verlag GmbH, Eggolsheim 2002, ISBN 3-89555-076-0 , p. 53 .
  • v. Kurrs Mineralreich in Pictures (3rd edition), edited by Prof. Dr. A. Kenngott in Zurich, Verlag JF Schreiber, Esslingen 1878 available online as PDF (3.5 MB)

Web links

Commons : Wittichenite  - collection of images, videos and audio files

Individual evidence

  1. ↑ a b c V. Kocman, EW Nuffield: The crystal structure of wittichenite, Cu 3 BiS 3 . In: Acta Crystallographica. B29 (1973), pp. 2528-2535 doi : 10.1107 / S0567740873006953
  2. ↑ Wittichenite , In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF 60.6 kB )
  3. ↑ a b Thomas Witzke : The discovery of Emplektit
  4. ^ Helmut Schrätze, Karl-Ludwig Weiner: Mineralogie. A textbook on a systematic basis . de Gruyter, Berlin; New York 1981, ISBN 3-11-006823-0 , pp. 289-290 .
  5. ↑ Mindat - number of sites for Wittichenit
  6. ↑ Find location list for Wittichenite in the Mineralienatlas and Mindat